Physics

Sound


Diffusion


The spreading out and mixing of a substance with another substance due to the motion of its particles is called diffusion. The diffusion of one substance into another substance goes on until a uniform mixture is formed. Let us take an example of diffusion. If we take a gas jar full of bromine vapours and invert

another gas jar containing air over it, then after some time, the red-brown vapours of bromine spread out into the upper gas jar containing air (see Figure 28). In this way, the upper gas jar which contains colourless air in it, also turns red-brown. This mixing is due to the diffusion of bromine vapour (or bromine gas) into ir. Air from the upper gas jar also diffuses into the lower gas jar though we cannot see it.
Diffusion is a property of matter which is based on the motion (or movements) of its particles.Diffusion occurs in gases, liquids and solids. Diffusion is fastest in gases and slowest in solids. The diffusion is fastest in gases because the particles in gases move very rapidly. The diffusion is slowest in Solids because the particles in solids do not move much. The diffusion in liquids is, however, much faster than that in solids. The rate of diffusion increases on increasing the temperature of the diffusing substance(by heating). This is because when the temperature of a substance is increased by heating, its particles gain inetic energy and move more rapidly. And this increase in the speed of the particles of a substance increases the rate of diffusion. Please note that the phenomenon of diffusion tells us that the particles of matter are onstantly moving.

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Notes


Sound - Notes
1. 3. Humidity of Air
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2. 2. Liquid to Gas Change : Boiling (or Vaporisation)
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3. 4. Wind Speed
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4. Effect of 'Heating' and 'Cooling' on a Saturated Solution
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5. 2. Latent Heat of Vaporisation (Liquid to Gas Change)
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6. 2. Surface Area of the Liquid
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7. Classification Of Matter As Solids, Liquids And Gases
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8. Matter is made of particles
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9. Properties of Liquids
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10. Why Solids, Liquids and Gases Have Different Properties
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11. 2. The Particles of Matter have Spaces Between Them
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12. Liquids
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13. Properties of Solids
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14. Sound - Study Points
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15. 1. Solid to Liquid Change : Melting
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16. 3. Gas to Liquid Change : Condensation
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17. Evaporation
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18. 1. Latent Heat of Fusion (Solid to Liquid Change)
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19. 1. Temperature
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20. Diffusion in Liquids
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21. Effect of Change of Temperture
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22. Latent heat
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23. 1. The Particles of Matter are Very, Very Small
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24. Gases
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25. 4. The Particles of Matter Attract Each Other
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26. Change of State of matter
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27. Effect of Change pressure
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28. 3. The Particles of Matter are Constantly Moving
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29. Characteristics of Particles of Matter
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30. 4. Liquid to Solid Change : Freezing
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31. Two More States of Matter : Plasma and Bose-Einstein Condensate
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32. Factors Affecting Evaporation
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33. Diffusion
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34. Cooling Caused by Evaporation
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35. Solids
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36. Dissolving a Solid in a Liquid
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37. Matter In Our Surroundings
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38. The Common Unit Of Temperature and Si Unit Of Temperatre
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39. Mixing of Two Gases
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40. To Show That Solids and Liquids Cannot be Compressed but Gases Can be Compressed Easily
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41. Evidence for Particles in Matter
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42. Sublimation
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43. Rigid and Fluid
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44. To Show that Liquids do not have a Fixed Shape but they have a Fixed Volume
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45. To Show the Presence of Water Vapour in Air
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46. Movement of Pollen Grains in Water
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47. Diffusion in Solids
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48. Diffusion in Gases
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49. Gases Can be Liquefied by Applying Pressure and Lowering Temperature
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50. To Show that Gases do not have a Fixed Shape or a Fixed Volume
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